There are instances where it is desirable to insert or implant into the body of a person an electrically conductive circuit, in particular a conducting wire. Examples may be to provide heating, an electrical connection between implanted components, an antenna or as any other electrical conduction part of a device. Electronic circuits used in the human body are typically isolated from the person's blood, tissue or interstitial fluids by physical barriers such as with coatings, sleeves, envelopes and so on. The present invention, described below, proposes the use of a bare electrical conductor and associated power supply system.
It is often necessary or desirable to occlude a body vessel. There are numerous known techniques to achieve this, the most invasive typically being by ligation of the vessel from outside. A number of endoluminal procedures are also known, such as by implantation of vascular plugs, embolization coils or particles, as well as by electrical methods including RF embolization. Implantation of a vessel blocking device, such as a coil or plug, leaves within the patient's body a foreign object, which can result in complications. Furthermore, the implanted device may not provide proper occlusion and/or may move over time, losing occlusive efficacy. RF embolization has been the subject of numerous studies. In particular two principal systems have been investigated, the first being a monopolar system in which a conductor providing an anode is placed endoluminally at the location at which it is desired to ablate the vessel, and a conductor providing a cathode pad is placed adjacent the patient, at a location as close as possible to the anode. The second system is a bipolar system in which both the anode and the cathode conductors are disposed in the vessel to be treated, for instance by being disposed on a common endoluminal carrier. RF embolization relies on passing current at RF frequencies through the electrode of the system and use of ionic conduction through the patient's blood or tissue. The RF energy causes heating of the blood or tissue and ablation either by generation of a blood clot or by collapse of the vessel due to the ablation energy. In theory such a system can work effectively, however, it does suffer from drawbacks. During the RF ablation process blood (or tissue) coagulates around the anode. Once this occurs the coagulation creates a current barrier with a resultant loss of ablation function. If ablation up to that point has not been sufficient to close the vessel, there will be incomplete occlusion. For this and other reasons, RF energy is supplied at a power high enough to seek to ensure that sufficient blood or vessel tissue is ablated to create a good enough seal of the vessel. However, this can result in an excess of energy and an excess of heating being applied to the vessel, with the risk that there can be damage to the vessel and/or nearby organs. For these and other reasons, RF ablation has had mixed results.
Examples of some prior art implantable conductive circuits are described in US-2011/0180421, U.S. Pat. Nos. 6,019,877, 6,189,536, US-2008/0283417, US-2010/0010640 and US-2008/0319501.